I can't speak to "over 50," but I can speak to "over 40." I founded my first software startup in 1995 while I was still an undergraduate. I had the good fortune of timing it so that after a year and a half of toil and obscurity we hit the wave of the dotcom boom, and I was able to establish myself as a proven serial entrepreneur and have been able to found a series of moderately successful tech companies over the years. I'm 42 now, and I'm currently getting a new startup off the ground with three other co-founders who are also in their early forties. We have the good fortune of all having had at least one big success in our careers, but I can attest that our experience has been valuable, and we haven't had a particularly hard time raising money.
I mention this because I think that there are a lot of people between 40 and 50 right now who are the first generation of true digital natives (for example, I have no idea what it was like to work in a pre-email office). Many of us weathered the dotcom boom and bust. From where I'm sitting, this cohort is quite well equipped to found successful tech companies, despite the fact that we tend to have families and children.